{"id":"CVE-2026-33540","state":"PUBLISHED","title":"Distribution affected by pull-through cache credential exfiltration via www-authenticate bearer realm","description":"Distribution is a toolkit to pack, ship, store, and deliver container content. Prior to 3.1.0, in pull-through cache mode, distribution discovers token auth endpoints by parsing WWW-Authenticate challenges returned by the configured upstream registry. The realm URL from a bearer challenge is used without validating that it matches the upstream registry host. As a result, an attacker-controlled upstream (or an attacker with MitM position to the upstream) can cause distribution to send the configured upstream credentials via basic auth to an attacker-controlled realm URL. This vulnerability is fixed in 3.1.0.","publishedAt":"2026-04-06T14:55:04.812Z","updatedAt":"2026-04-06T15:04:50.154Z","severity":{"score":7.5,"label":"High","version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N","source":"GitHub_M"},"assigner":"GitHub_M","products":["distribution distribution"],"affected":[{"vendor":"distribution","product":"distribution","versions":[{"version":"< 3.1.0","status":"affected"}]}],"references":["https://github.com/distribution/distribution/security/advisories/GHSA-3p65-76g6-3w7r"],"weaknesses":["CWE-918"],"ingestedAt":"2026-10-29T20:11:40.391Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/33xxx/CVE-2026-33540.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-33540","state":"PUBLISHED","datePublished":"2026-04-06T14:55:04.812Z","dateUpdated":"2026-04-06T15:04:50.154Z","assignerShortName":"GitHub_M","assignerOrgId":"a0819718-46f1-4df5-94e2-005712e83aaa","dateReserved":"2026-03-20T18:05:11.831Z"},"containers":{"cna":{"title":"Distribution affected by pull-through cache credential exfiltration via www-authenticate bearer realm","descriptions":[{"lang":"en","value":"Distribution is a toolkit to pack, ship, store, and deliver container content. Prior to 3.1.0, in pull-through cache mode, distribution discovers token auth endpoints by parsing WWW-Authenticate challenges returned by the configured upstream registry. The realm URL from a bearer challenge is used without validating that it matches the upstream registry host. As a result, an attacker-controlled upstream (or an attacker with MitM position to the upstream) can cause distribution to send the configured upstream credentials via basic auth to an attacker-controlled realm URL. This vulnerability is fixed in 3.1.0."}],"affected":[{"vendor":"distribution","product":"distribution","versions":[{"version":"< 3.1.0","status":"affected"}]}],"references":[{"url":"https://github.com/distribution/distribution/security/advisories/GHSA-3p65-76g6-3w7r","name":"https://github.com/distribution/distribution/security/advisories/GHSA-3p65-76g6-3w7r","tags":["x_refsource_CONFIRM"]}],"metrics":[{"cvssV3_1":{"attackComplexity":"LOW","attackVector":"NETWORK","availabilityImpact":"NONE","baseScore":7.5,"baseSeverity":"HIGH","confidentialityImpact":"HIGH","integrityImpact":"NONE","privilegesRequired":"NONE","scope":"UNCHANGED","userInteraction":"NONE","vectorString":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N","version":"3.1"}}],"problemTypes":[{"descriptions":[{"cweId":"CWE-918","lang":"en","description":"CWE-918: Server-Side Request Forgery (SSRF)","type":"CWE"}]}],"providerMetadata":{"shortName":"GitHub_M","orgId":"a0819718-46f1-4df5-94e2-005712e83aaa","dateUpdated":"2026-04-06T14:55:04.812Z"},"source":{"advisory":"GHSA-3p65-76g6-3w7r","discovery":"UNKNOWN"}},"adp":[{"title":"CISA ADP Vulnrichment","references":[{"url":"https://github.com/distribution/distribution/security/advisories/GHSA-3p65-76g6-3w7r","tags":["exploit"]}],"metrics":[{"other":{"type":"ssvc","content":{"timestamp":"2026-04-06T15:04:46.763761Z","id":"CVE-2026-33540","options":[{"Exploitation":"poc"},{"Automatable":"yes"},{"Technical Impact":"partial"}],"role":"CISA Coordinator","version":"2.0.3"}}}],"providerMetadata":{"shortName":"CISA-ADP","orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","dateUpdated":"2026-04-06T15:04:50.154Z"}}]}}}